From 18e903c4fae06abc2a20344146eae3dfeae53f6b Mon Sep 17 00:00:00 2001
From: etiennebacher <etienne.bacher@protonmail.com>
Date: Sat, 28 Dec 2024 00:17:10 +0100
Subject: [PATCH] improve following comment

---
 .../src/chunked_array/strings/normalize.rs    | 35 +++++++++++++------
 1 file changed, 25 insertions(+), 10 deletions(-)

diff --git a/crates/polars-ops/src/chunked_array/strings/normalize.rs b/crates/polars-ops/src/chunked_array/strings/normalize.rs
index 7f974b7bdde2..29c4939d5679 100644
--- a/crates/polars-ops/src/chunked_array/strings/normalize.rs
+++ b/crates/polars-ops/src/chunked_array/strings/normalize.rs
@@ -1,5 +1,4 @@
-use polars_core::prelude::arity::unary_elementwise;
-use polars_core::prelude::StringChunked;
+use polars_core::prelude::{StringChunked, StringChunkedBuilder};
 use unicode_normalization::UnicodeNormalization;
 
 #[derive(Clone, Eq, PartialEq, Hash, Debug)]
@@ -11,13 +10,29 @@ pub enum UnicodeForm {
     NFKD,
 }
 
+pub fn normalize_with<F: Fn(&str, &mut String)>(
+    ca: &StringChunked,
+    normalizer: F,
+) -> StringChunked {
+    let mut buffer = String::new();
+    let mut builder = StringChunkedBuilder::new(ca.name().clone(), ca.len());
+    for opt_s in ca.iter() {
+        if let Some(s) = opt_s {
+            buffer.clear();
+            normalizer(s, &mut buffer);
+            builder.append_value(&buffer);
+        } else {
+            builder.append_null();
+        }
+    }
+    builder.finish()
+}
+
 pub fn normalize(ca: &StringChunked, form: UnicodeForm) -> StringChunked {
-    unary_elementwise(ca, |val| {
-        val.map(|x| match form {
-            UnicodeForm::NFC => x.nfc().collect::<String>(),
-            UnicodeForm::NFKC => x.nfkc().collect::<String>(),
-            UnicodeForm::NFD => x.nfd().collect::<String>(),
-            UnicodeForm::NFKD => x.nfkd().collect::<String>(),
-        })
-    })
+    match form {
+        UnicodeForm::NFC => normalize_with(ca, |s, b| b.extend(s.nfc())),
+        UnicodeForm::NFKC => normalize_with(ca, |s, b| b.extend(s.nfkc())),
+        UnicodeForm::NFD => normalize_with(ca, |s, b| b.extend(s.nfd())),
+        UnicodeForm::NFKD => normalize_with(ca, |s, b| b.extend(s.nfkd())),
+    }
 }